Device for closing filled bags

ABSTRACT

The invention relates to a device for closing filled bags ( 1 ). Such a device is arranged in view of high filling frequencies in an installation for filling bags such that a first belt conveyor ( 2 ) is provided which acts in the closure area of the bags ( 1 ) wherein the first belt conveyor ( 2 ) is assigned to a single conveyor ( 3 ) for transporting the bags ( 1 ) and the outlet of the first belt conveyor ( 2 ) is assigned to the inlet of a heat-sealing station ( 4 ).

[0001] The invention relates to a device for closing filled bags.

[0002] Bags in the sense of the invention are especially to be understood as stepped-end bags, but as also simple bags or folding bags. Such bags are increasingly used as packaging in the food and non-food areas and both for liquid or at least partly liquid filling materials and also for pourable filling materials. The device for closing filled bags according to the invention is provided for use within apparatus and processes for filling bags which ensure high filling frequencies. Such a device and a corresponding method are described for example, in the subsequently published Patent Application PCT/EP00/04541 which is also attributable to the applicant.

[0003] Devices for filling bags known for some time from the prior art operate in a clocked fashion and accordingly provide only low filling frequencies of around 20 to 30 bags per minute in contrast to continuously operating devices for filling for example glass or polyethylene bottles. In contrast, known devices for filling for example glass or polyethylene bottles are capable of achieving filling frequencies of 1000 or more containers per minute. Since it has not yet been possible to achieve these high filling frequencies when filling bags, the use of bags is currently substantially restricted to products which are not produced in very high quantities.

[0004] As a result of the low filling frequencies currently attainable with the conventional devices for filling bags, the problem arises that installations which can be used to produce bags in addition to filling and closing bags have so far hardly been used. This results from the fact that machines for producing high-quality bags impose very high requirements on the mechanical equipment and thus require investments which can generally only be economically justified if the bags are produced at a very high frequency. This currently has the result that equipment for filling bags is generally operated using bags pre-manufactured at another location which are merely filled and sealed in the known devices for filling bags, which only ensure low frequencies.

[0005] A device for filling bags which should make it possible to achieve high filling frequencies requires a series of measures for handling the bags which ensure the high frequencies at the respective stations, for example also at the heat-sealing station. The problem especially arises as to how the filled bags can be transferred at high frequency to a suitable heat-sealing station, for example, to a sealing star described in PCT/EP00/04541. During this transfer attention should be paid to the fact that the closure area of the bags must be placed exactly between the sealing jaws of the sealing star to ensure a problem-free seal. It has been found that such a transfer cannot be achieved by the arrangement of a simple mechanical slot, which in principle would ensure exact positioning transverse to the direction of transport, because as a result of the friction between the filled bags and the boundaries of the slot, the bags are pushed into the bag carriers used to transport the bags so that the closure area of the bags would be inserted between the sealing jaws at an angle.

[0006] Starting from the problems described previously, the object of the present invention is to provide a device for closing filled bags which ensures problem-free transfer of the filled bags to a heat-sealing station at high to very high filling frequencies.

[0007] The object derived and indicated previously is solved according to the invention by the fact that a device for closing filled bags has a first belt conveyor acting in the closure area of the bag, wherein the first belt conveyor is assigned to a single conveyor for transporting the bags and the outlet of the first belt conveyor is assigned to the inlet of a heat-sealing station. Since no simple mechanical slot is provided according to the invention for positioning the closure area of the bags relative to the sealing jaws of the heat-sealing station, but an “active” slot is formed by a first belt conveyor, it is ensured that the closure area of the bags is optimally transferred between the heat-sealing jaws of a heat-sealing station. In this case, the transport speeds of the single conveyor match those of the first belt conveyor.

[0008] According to one embodiment of the device for closing a filled bag according to the invention, a second belt conveyor is arranged in the direction of transport before the first belt conveyor, wherein the second belt conveyor acts on the bags in the direction of the vertical axis of the bags below the working surface of the first belt conveyor and the first belt conveyor and the second belt conveyor are arranged in an overlapping fashion in the direction of transport. This arrangement ensures that the headspace of the bag, i.e., the unfilled head area of the bag, can be very substantially reduced in volume by pressing together with the aid of the second belt conveyor, which is desirable with regard to the desired minimisation of the packing volume for a given filling quantity.

[0009] Finally, as a result of the limited space relationships during the direct transfer between the first belt conveyor and the heat-sealing station, it can be advantageous to arrange the device according to the invention such that a simple mechanical slot for transfer is provided at the outlet of the first belt conveyor.

[0010] There are now numerous possibilities for arranging and further developing the device for closing filled bags according to the invention. For this purpose reference is made for example to the claims subordinate to claim 1 on the one hand and to the description of a preferred exemplary embodiment in connection with the drawings on the other hand. In the figures:

[0011]FIG. 1 shows a top view of the transfer region between a single conveyor and a sealing star with a first exemplary embodiment of a device for closing filled bags according to the invention arranged in the transfer region and

[0012]FIG. 2 shows a side view of the exemplary embodiment of a device for closing filled bags according to the invention.

[0013] The top view of FIG. 1 shows a device for closing filled bags 1 according to the invention comprising a first belt conveyor 2 acting in the closure area of the bags 1, wherein the first belt conveyor is assigned to a single conveyor 3 for transporting the bags 1 and the outlet of the first belt conveyor 2 is assigned to the inlet of a heat-sealing station 4 executed as a sealing star. The bags 1 are transported by means of bag carriers 5, as has already been described in PCT/EP00/04541, both on the single conveyor 3 and in the heat-sealing station 4.

[0014] The first belt conveyor 2 transfers the closure area of the bags 1 at its outlet in an exactly predetermined position between two sealing jaws 6. These sealing jaws 6 then close in a known fashion and provide by means of appropriate temperature and pressure a closure of the closure area of the bags 1 by a heat-seal seam.

[0015] The bags 1 are transported continuously at high speed with the aid of the bag carriers 5, the single conveyor 3, the first belt conveyor 2 and the heat-sealing station 4 and thus high filling frequencies and high sealing frequencies respectively can be achieved for the bags to be processed.

[0016] In addition to the first belt conveyor 2, the exemplary embodiment shown in FIG. 1 comprises a second belt conveyor 7 before the first belt conveyor 2 in the direction of transport. The second belt conveyor 7 acts on the bags 1 in the direction of the vertical axis of the bags 1 below the working surface of the first belt conveyor 2 and the first belt conveyor 2 and the second belt conveyor 7 are arranged in an overlapping fashion in the direction of transport.

[0017] This arrangement of the device for closing filled bags 1 according to the invention is shown particularly clearly in FIG. 2. The second belt conveyor 7 arranged before the first belt conveyor 2 reduces the air-filled headspace above the filling volume of the bags 1 by acting below the closure area of the bags 1. This reduction in the headspace is maintained by the fact that the second belt conveyor 7 and the first belt conveyor 2 are arranged in an overlapping fashion so that during the transfer from the second belt conveyor 7 to the first belt conveyor 2 no air can flow into the headspace. As a result of a reduced pack volume of bags with reduced headspace, a significantly more economical mode of operation is obtained for the described closure of the bags 1.

[0018] Finally, in FIG. 2 there is provided a mechanical slot 8 arranged at the outlet of the first belt conveyor 2 which makes possible the transfer between the first belt conveyor 2 and the heat-sealing station 4 also with restricted space relationships.

[0019] In addition, it should merely be noted that the conveying speeds of the belt conveyors 2, 7, of the single conveyor 3 and of the heat-sealing station 4 are selected as matching. In this case, the belt conveyors 2, 7 do not actually act as genuine conveyors which apply force to convey the bags 1, but rather as belt gaps which prevent friction-induced forces in the opposite direction to the direction of transport from appearing in the slot required for the positioning.

[0020] The bag carriers 5 are arranged, as can be seen from FIG. 2, such that they have a base plate 9 and two guide rails 10 located vertically on this base plate. 

1. A device for closing filled bags (1) comprising a first belt conveyor (2) which acts in the closure area of the bags (1), wherein the first belt conveyor (2) is assigned to a single conveyor (3) for transporting the bags (1) and the outlet of the first belt conveyor (2) is assigned to the inlet of a heat-sealing station (4).
 2. The device according to claim 1, characterised in that in the direction of transport a second belt conveyor (7) is arranged in front of the first belt conveyor (2), that the second belt conveyor (7) acts on the bags (1) in the direction of the vertical axis of the bags (1) below the working surface of the first belt conveyor (2) and that the first belt conveyor (2) and the second belt conveyor (7) are arranged in an overlapping fashion in the direction of transport.
 3. The device according to claim 1 or claim 2, characterised in that at the outlet of the first belt conveyor (2) a simple mechanical slot (8) is provided for transfer. 